Hydraulic fracturing is used to fracture rock surrounding a treatment well and pump the created fractures with a mixture of fluid and granular media (proppant) to enhance the permeability of the rock formation the treatment well. If the formation contains a hydrocarbon reservoir, treatments such as hydraulic fracturing seek to increase the production of the reservoir by creating pathways through which the hydrocarbons can flow to the treatment well. A typical scenario is in gas-bearing shale formations where the inherent permeability of the rock is too low to allow for efficient drainage of the reservoir. Hydraulic fracturing allows for the gas trapped in pore spaces of the shale to be produced, even from long distances from a production well, due to the enhanced permeability of the hydrocarbon-bearing formation that the injected proppant imparts.
Given the underground location in the reservoir and small size of the formations it is difficult to predict how the reservoir will behave in response to hydraulic fracturing.
In the process of creating and reactivating cracks in the formation, hydraulic fracturing generates small-scale seismic events. This, seismic energy generated by these events propagates away from the location of the fracture, which is known as the hypocenter. These seismic events, called microseismic events, typically measure less than 0 on the moment magnitude scale. In contrast, earthquakes that are felt by humans and reported on surface need to reach magnitudes of 3 or more.
Microseismic events caused by the hydraulic fracturing can be used to monitor and model the effect of hydraulic fracturing on the reservoir. Improved methods, devices, and systems for monitoring and modeling hydraulic fracturing are desirable.